Yeah, ive just read about that... How hard is it for a beginner to begin to re-create a mp3 (something like a video game tune) to a mod format?
How hard? Depends on a lot of things. How long is a piece of string and how many ants would it require to build a space station? Just joking. It's all about whether you yourself will adapt to the tools.
If you want to learn more about how to track, have a look around the forums, as it is quite off topic on this thread. There are tutorials around as well, a couple of threads in the general direction are floating around (try the search), and of course you can always start a thread in the main Music Discussion forum. You could also potentially ask in the
MilkyTracker forum (this is their own subset of forums, staffed by their developer), as that's a piece of software specifically for tracking modules in the style of FastTracker 2 (it's directed at oldskool composers though, since FT2 won't run on windows and MT does). Other stuff to try is Modplug tracker (modplug.com), also windows based.
couldn't you just convert the mp3 into a wav and make a one sample, one note mod that lasts long enough, and put that file in the game
It would be turned back to you by the developer, probably in disgust. MODs are meant to be small, especially for games where pre-loading a massive single sample is out of the question
Let's say your MP3 is 3 minutes long, and assuming you didn't want it to sound like an 8 bit, extremely low sample rate piece of crap - you would have to wait to load a 30MB WAV sample, or stream it - but I doubt streaming is a capable task given the limited capacity of both of the DS's processors.
A quality 16 bit audio uncompressed PCM stream is approximately 10 times the size of an MP3 at 128kbps. It's also probably going to be stored in an uncompressed module file, which just acts as a wrapper. I don't know the specifics of what this chap's developer is like, but this way you suggested is surely a big fat lazy way of fulfilling the requirements.
I dare say, some people have relied on using this exact method, but I would not go so far as to say it is method of best practice. Far from it.